[A simultaneous determination of various main components in oriental pharmaceutical decoction "heii-san" by ion-pair high-performance liquid chromatography].

A simple and precise method was established for the simultaneous determination of five selected marker components in oriental pharmaceutical decoction "Heii-San" by means of high-performance liquid chromatography using tetra-n-amylammonium bromide (TAA) as an ion-pair reagent. For the separation of these five components, such as hesperidin (1), 6-gingerol (2), honokiol (3), glycyrrhizin (4) and magnolol (5), an ODS column was used with multi-step gradient elution with 10 mM TAA (H3PO4, pH 4.0)-acetonitrile. The acetonitrile content linearly increased from 25 to 90%. This method was compared with other three methods, i.e. a water-acetonitrile method, a phosphate buffer method and an ion-suppression method. Five main components were eluted within 50 min without interference from co-existing components.